/*
 * ProGuard -- shrinking, optimization, obfuscation, and preverification of Java bytecode.
 *
 * Copyright (c) 2002-2018 GuardSquare NV
 *
 * This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public
 * License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later
 * version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied
 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along with this program; if not, write to the Free
 * Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */
package proguard.classfile.util;

import a.annotation.proguard.classfile.attribute.annotation.*;
import proguard.classfile.*;
import proguard.classfile.attribute.CodeAttribute;
import proguard.classfile.attribute.annotation.visitor.ElementValueVisitor;
import proguard.classfile.attribute.visitor.AllAttributeVisitor;
import proguard.classfile.constant.*;
import proguard.classfile.constant.visitor.ConstantVisitor;
import proguard.classfile.instruction.*;
import proguard.classfile.instruction.visitor.*;
import proguard.classfile.visitor.MemberVisitor;

/**
 * This ElementValueVisitor initializes the field references of the EnumConstantElementValue instances that it visits.
 *
 * @author Eric Lafortune
 */
public class EnumFieldReferenceInitializer extends SimplifiedVisitor
    implements ElementValueVisitor, InstructionVisitor, ConstantVisitor {
    // *
    private static final boolean DEBUG = false;
    /*/
    private static       boolean DEBUG = true;
    //*/

    private MemberVisitor enumFieldFinder = new AllAttributeVisitor(new AllInstructionVisitor(this));

    // Fields acting as parameters and return values for the visitors.
    private String enumTypeName;
    private String enumConstantName;
    private boolean enumConstantNameFound;
    private Clazz referencedEnumClass;
    private Field referencedEnumField;

    // Implementations for ElementValueVisitor.

    public void visitAnyElementValue(Clazz clazz, Annotation annotation, ElementValue elementValue) {}

    public void visitEnumConstantElementValue(Clazz clazz, Annotation annotation,
        EnumConstantElementValue enumConstantElementValue) {

        if (enumConstantElementValue.referencedClasses != null
            && enumConstantElementValue.referencedClasses.length > 0) {
            referencedEnumClass = enumConstantElementValue.referencedClasses[0];
            if (referencedEnumClass != null) {
                // Try to find the enum field through the static enum
                // initialization code (at least for program classes).
                enumTypeName = enumConstantElementValue.getTypeName(clazz);
                enumConstantName = enumConstantElementValue.getConstantName(clazz);
                referencedEnumField = null;
                referencedEnumClass.methodAccept(ClassConstants.METHOD_NAME_CLINIT, ClassConstants.METHOD_TYPE_CLINIT,
                    enumFieldFinder);

                // Otherwise try to find the enum field through its name.
                // The constant name could be different from the field name, if
                // the latter is already obfuscated.
                if (referencedEnumField == null) {
                    referencedEnumField = referencedEnumClass.findField(enumConstantName, enumTypeName);
                }

                if (DEBUG) {
                    System.out.println("EnumFieldReferenceInitializer: [" + referencedEnumClass.getName() + "."
                        + enumConstantName + "] -> " + referencedEnumField);
                }

                enumConstantElementValue.referencedField = referencedEnumField;
            }
        }
    }

    // Implementations for InstructionVisitor.

    public void visitAnyInstruction(Clazz clazz, Method method, CodeAttribute codeAttribute, int offset,
        Instruction instruction) {}

    public void visitConstantInstruction(Clazz clazz, Method method, CodeAttribute codeAttribute, int offset,
        ConstantInstruction constantInstruction) {
        switch (constantInstruction.opcode) {
            case InstructionConstants.OP_LDC:
            case InstructionConstants.OP_LDC_W:
            case InstructionConstants.OP_PUTSTATIC:
                clazz.constantPoolEntryAccept(constantInstruction.constantIndex, this);
                break;
        }
    }

    // Implementations for ConstantVisitor.

    public void visitAnyConstant(Clazz clazz, Constant constant) {}

    public void visitStringConstant(Clazz clazz, StringConstant stringConstant) {
        enumConstantNameFound = enumConstantName.equals(stringConstant.getString(clazz));
    }

    public void visitFieldrefConstant(Clazz clazz, FieldrefConstant fieldrefConstant) {
        if (enumConstantNameFound) {
            if (enumTypeName.equals(fieldrefConstant.getType(clazz))) {
                referencedEnumField = (Field)fieldrefConstant.referencedMember;
            }

            enumConstantNameFound = false;
        }
    }
}